by Emily Goebel, MD FRCPC, reviewed and updated on October 31, 2018
The vulva is the external part of the female genital tract. It forms the opening of the vagina and includes the mons pubis, labia majora, labia minora and clitoris. The vulva is composed of skin. The surface of the skin is called the epidermis and is mostly made up of squamous cells. The tissue beneath the epidermis is called the dermis, it contains blood vessels and connective tissue.
Extramammary Paget disease is a cancer that develops in the epidermis of the vulva. It is considered a type adenocarcinoma.
The cancer cells in extramammary Paget disease usually stay in the epidermis. If cancer cells are also seen in the dermis, this will be described in your report.
This diagnosis is usually made after a small sample of tissue is removed in a procedure called a biopsy. The entire tumour will usually be removed fully in a larger surgical procedure called an excision or vulvectomy.
A margin is any tissue that has to be cut by the surgeon in order to remove the tumour from your body. A negative margin means that no cancer cells were seen at the cut edge of the tissue. In contrast, a positive margin means that cancer cells were seen at the cut edge of the tissue. A positive margin increases the risk that the tumour will grow back in that location.
Your pathologist may perform a test called immunohistochemistry to confirm the diagnosis and to exclude other cancers that may look similar to extramammary Paget disease.
The tumour cells will be positive or reactive for immunohistochemical markers such as CK7 and GCDFP-15 and negative or non-reactive for p63 and S100, which you may see included in your pathology report.